Automated Pulsed Eddy Current Method for Detection and Classification of Hidden Corrosion

Corrosion has an important effect on the structural integrity of aging aircraft components, and an automatic and effective method of corrosion detection and classification can help to ensure the safe operation of a transportation system. Pulsed eddy current (PEC) has been shown to effectively characterize hidden corrosion in aircraft fuselage lap joints. However, two noise sources in the form of probe lift-off and interlayer gap can cause false indications or inaccuracies in quantification. This paper describes the development of a modular architecture for analysis of PEC data to enable automatic characterization of hidden corrosion in a typical aircraft fuselage multi-layer structure. The goal of this study was to develop a software tool to detect and distinguish between first layer and second layer corrosion damage. This investigation is a follow on to previous work that applied time-frequency analysis of PEC signals to provide specific visual patterns related to the interlayer gap, lift-off, and material loss. In the present work, the authors have investigated the time-frequency analysis of PEC signals along with feature extraction and classification to automatically characterize and determine the location of material loss in a two-layer structure.